-qtune

Pragma equivalent

None.

Purpose

Tunes instruction selection, scheduling, and other architecture-dependent performance enhancements to run best on a specific hardware architecture.

Syntax


                 .-balanced-.   
>>- -q--tune--=--+-auto-----+----------------------------------><
                 +-604------+   
                 +-ppc970---+   
                 +-pwr3-----+   
                 +-pwr4-----+   
                 +-403------+   
                 +-pwr5-----+   
                 +-pwr6-----+   
                 +-pwr7-----+   
                 +-rs64a----+   
                 +-rs64b----+   
                 '-rs64c----'

Defaults

-qtune=balanced when the default -qarch setting is in effect. Otherwise, the default depends on the effective -qarch setting. See Table 1 for details.

Parameters

403: Optimizations are tuned for the PowerPC 403 processor.
604: Optimizations are tuned for the PowerPC® 604 processor.
auto: Optimizations are tuned for the platform on which the application is compiled.
balanced: Optimizations are tuned across a selected range of recent hardware.
ppc970: Optimizations are tuned for the PowerPC 970 processor.
pwr3: Optimizations are tuned for the POWER3 hardware platforms.
pwr4: Optimizations are tuned for the POWER4 hardware platforms.
pwr5: Optimizations are tuned for the POWER5 hardware platforms.
pwr6: Optimizations are tuned for the POWER6® hardware platforms.
pwr7: Optimizations are tuned for the POWER7® hardware platforms.
rs64a: Optimizations are tuned for the RS64I processor.
rs64b: Optimizations are tuned for the RS64II processor.
rs64c: Optimizations are tuned for the RS64III processor.

Note: As of the V9.0 release of the compiler, suboptions representing 601, 602, 603, POWER® and POWER2 architectures are deprecated.

Usage

If you want your program to run on more than one architecture, but to be tuned to a particular architecture, you can use a combination of the -qarch and -qtune options. These options are primarily of benefit for floating-point intensive programs.

By arranging (scheduling) the generated machine instructions to take maximum advantage of hardware features such as cache size and pipelining, -qtune can improve performance. It only has an effect when used in combination with options that enable optimization.

Although changing the -qtune setting may affect the performance of the resulting executable, it has no effect on whether the executable can be executed correctly on a particular hardware platform.

Acceptable combinations of -qarch and -qtune are shown in the following table.

Table 1. Acceptable **-qarch/-qtune** combinations
-qarch option	Default -qtune setting	Available -qtune settings
403	403	auto \| 403
604	604	auto \| 604
ppc	balanced	auto \| 604 \| rs64a \| rs64b \| rs64c \| pwr3 \| pwr4 \| pwr5 \| pwr6 \| pwr7 \| ppc970 \| balanced
ppcgr	balanced	auto \| 604 \| rs64b \| rs64c \| pwr3 \| pwr4 \| pwr5 \| pwr6 \| pwr7 \| ppc970 \| balanced
ppc64	balanced	auto \| rs64a \| rs64b \| rs64c \| pwr3 \| pwr4 \| pwr5 \| pwr6 \| pwr7 \| ppc970 \| balanced
ppc64gr	balanced	auto \| rs64b \| rs64c \| pwr3 \| pwr4 \| pwr5 \| pwr6 \| pwr7 \| ppc970 \| balanced
ppc64grsq	balanced	auto \| rs64b \| rs64c \| pwr3 \| pwr4 \| pwr5 \| pwr6 \| pwr7 \| ppc970 \| balanced
ppc64v	ppc970	auto \| ppc970 \| pwr6 \| balanced
ppc970	ppc970	auto \| ppc970 \| balanced
pwr3	pwr3	auto \| pwr3 \| pwr4 \| pwr5 \| pwr7 \| ppc970 \| balanced
pwr4	pwr4	auto \| pwr4 \| pwr5 \| pwr7 \| ppc970 \| balanced
pwr5	pwr5	auto \| pwr5 \| pwr7 \| balanced
pwr5x	pwr5	auto \| pwr5 \| pwr7 \| balanced
pwr6	pwr6	auto \| pwr6 \| pwr7 \| balanced
pwr6e	pwr6	auto \| pwr6 \| balanced
pwr7	pwr7	auto \| pwr7 \| balanced
rs64a	rs64a	auto \| rs64a
rs64b	rs64b	auto \| rs64b
rs64c	rs64c	auto \| rs64c

Predefined macros